§1.1 Field of the Invention
The present invention concerns eliminating or suppressing parallel plate or surface-wave radiations, particularly in the context of printed-circuits, chip packages and antennas. In particular, the present invention concerns providing an improved substrate arrangement employing a unidirectional conducting dielectric substrate to be used with slotline circuits and microstrip antenna designs so as to eliminate or greatly suppress parallel plate or surface-wave radiations.
§1.2 Background Information
Printed circuits have been developed and used for commercial and military applications during the past decades. Such printed circuits have provided significant benefits in microwave and antenna technologies. Printed elements physically require a dielectric substrate to connect to the rest of the circuit in a multilayered structure. For such dielectric-supported geometries, energy leakage occurs in the form of surface waves.
More specifically, designs commonly implemented today use conventional substrates that are uniform and isotropic in their electromagnetic characteristics. These substrates support one or more guided-wave modes, as dictated by fundamental electromagnetic theory. A circuit or antenna element fabricated on such a substrate would excite power into one or more of these guided modes which propagate along the substrate. As a result, valuable radio-frequency power is lost, making such designs inefficient. These guided radiations also create unwanted cross-talk between nearby circuits, introduce packaging resonances that may seriously affect the system performance, and/or create various electromagnetic interference problems that could seriously degrade signal integrity of the chip or system.
References directed to problems in printed circuits include: the article H.-Y. D. Yang, J. Wang “Surface Waves of Printed Antennas on Planar Artificial Periodic Dielectric Structures” Antennas and Propagation, IEEE Transactions on, Volume 49, Issue 3, (March 2001); and the reference J. H. Kim “Multilayer Printed Circuits With a Uniaxial Conducting Layer” Master Thesis, (January 2006, Polytechnic University of New York). Each of the foregoing references is expressly incorporated by reference.
It would be useful to reduce, and possibly eliminate, such surface waves and consequently, problems associated with such surface waves.